A medical agent, which has been sold under the brand name of “Neurotropin”, contains a nonprotein extract from the inflamed skin of rabbits following inoculation with vaccinia virus as an active ingredient. Neurotropin (NTP) has been widely used to treat neuropathic pain, including post-herpetic neuralgia and low back pain in Japan. In animal models, NTP has been shown that the anti-nociceptive effect was derived by the activation of the descending monoaminergic pain inhibitory system. NTP has also been shown to inhibit the pain pathway by inhibiting activation of the kallikrein-kinin cascade and, consequently, the formation of bradykinin in vitro and in vivo.
The suppressive effect of NTP on tumor necrosis factor-α (TNF-α) and cyclooxygenase-2 (COX-2) mRNA expression by human intervertebral disc cells was recently reported. However, it is not clear if NTP has an effect on intervertebral disc cell extracellular matrix (ECM) synthesis.